sagemathgh-40689: remove boost_cropped spkg, add boost to prereqs
    
boost is available on all the supported platforms, and maintaining the
spkg thus makes no sense any more. So e.g sagemath#34748 can be closed

### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
    
URL: sagemath#40689
Reported by: Dima Pasechnik
Reviewer(s): Antonio Rojas, Dima Pasechnik

Author: Release Manager

.github/workflows/dist.yml

@@ -185,7 +185,7 @@ jobs:
       # SPKGs to install as system packages
       SPKGS: _bootstrap _prereq
       # Non-Python packages to install as spkgs
-      TARGETS_PRE: gmp mpfr mpc bliss coxeter3 mcqd meataxe sirocco boost_cropped tdlib
+      TARGETS_PRE: gmp mpfr mpc bliss coxeter3 mcqd meataxe sirocco tdlib
       CIBW_BUILD: "*${{ matrix.build }}*"
       # Disable building PyPy wheels on all platforms
       CIBW_SKIP: "pp*"

COPYING.txt

@@ -33,7 +33,6 @@ SOFTWARE                    LICENSE
 -----------------------------------------------------------------------
 boehm_gc                    MIT-like license (see below)
 backports_ssl_match_hostname  Python License
-boost_cropped               Boost Software License (see below)
 cddlib                      GPLv2+
 certifi                     ISC
 cliquer                     GPLv2+
@@ -795,35 +794,6 @@ simplicity, included in its entirety.
 
 ================================================================================
 
-boost_cropped:
-(http://www.boost.org/LICENSE_1_0.txt)
-
-Boost Software License - Version 1.0 - August 17th, 2003
-
-Permission is hereby granted, free of charge, to any person or organization
-obtaining a copy of the software and accompanying documentation covered by
-this license (the "Software") to use, reproduce, display, distribute,
-execute, and transmit the Software, and to prepare derivative works of the
-Software, and to permit third-parties to whom the Software is furnished to
-do so, all subject to the following:
-
-The copyright notices in the Software and this entire statement, including
-the above license grant, this restriction and the following disclaimer,
-must be included in all copies of the Software, in whole or in part, and
-all derivative works of the Software, unless such copies or derivative
-works are solely in the form of machine-executable object code generated by
-a source language processor.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
-SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
-FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
-ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
-DEALINGS IN THE SOFTWARE.
-
-================================================================================
-
 bzip2:
 (http://www.bzip.org/)
 This program, "bzip2", the associated library "libbzip2", and all

Makefile

@@ -156,6 +156,7 @@ misc-clean:
 	rm -f aclocal.m4 config.log confcache
 	rm -rf autom4te.cache
 	rm -f build/make/Makefile build/make/Makefile-auto
+	rm -f build/platform/meson/sage-configure-native-file.ini
 	rm -rf src/lib
 
 bdist-clean: clean

build/bin/sage-build-env

@@ -88,6 +88,13 @@ if [ "x$SAGE_BUILD_ENV_SOURCED" = "x" ]; then
         export SAGE_CONFIGURE_PARI="--with-pari=$SAGE_PARI_PREFIX"
     fi
 
+    # This is usually blank if the system boost is used
+    if [ -n "$SAGE_BOOST_PREFIX" ]; then
+        # Some packages that depend on boost accept a --with-boost=<prefix> flag to
+        # their ./configure scripts. Thus we deal with this just as with GMP above.
+        export SAGE_CONFIGURE_BOOST="--with-boost=$SAGE_BOOST_PREFIX"
+    fi
+
     # Optimization flags.
     #
     # The compiler flags are set in order of priority by

build/bin/sage-build-env-config.in

@@ -58,6 +58,8 @@ export SAGE_SUITESPARSE_PREFIX="@SAGE_SUITESPARSE_PREFIX@"
 
 export SAGE_CONFIGURE_FFLAS_FFPACK="@SAGE_CONFIGURE_FFLAS_FFPACK@"
 
+export SAGE_BOOST_PREFIX="@SAGE_BOOST_PREFIX@"
+
 export SAGE_HAVE_LIBJPEG="@SAGE_HAVE_LIBJPEG@"
 
 export SAGE_FRICAS_LISP="@SAGE_FRICAS_LISP@"

build/pkgs/_prereq/SPKG.rst

@@ -20,6 +20,6 @@ ca-certificates
 coreutils
 patch
 bzip2
-patch
 pkgconf
 zlib-dev
+boost

build/pkgs/_prereq/distros/alpine.txt

@@ -21,3 +21,5 @@ which
 patch
 pkgconf
 zlib
+boost
+libboost-devel

build/pkgs/_prereq/distros/arch.txt

@@ -19,3 +19,4 @@ bzip2
 pkg-config
 zlib
 zlib-devel
+libboost-devel

build/pkgs/_prereq/distros/conda.txt

@@ -32,3 +32,4 @@ ca-certificates
 patch
 pkg-config
 libz-dev
+libboost-dev